Perfluoro-3,6-dioxa-4-methyloct-7-enesulphonyl fluoride, perfluoro(4-methyl-3,6-dioxaoct-7-ene)sulfonyl fluoride, perfluoro(4-methyl-3,6-dioxaoct-7-ene)sulphonyl fluoride, Perfluoro-[2-(2-fluorosulfonylethoxy)propyl vinyl ether], 5-trifluoroethoxy-4-trifluoromethyl-3-oxa-1,1,2,2,4,5,5-heptafluorosulfonyl fluoride, 1,1,2,2-tetrafluoro-2-({1,1,1,2,3,3-hexafluoro-3-[(trifluorovinyl)oxy]-2-propanyl}oxy)ethanesulfonyl fluoride, perfluoro(4-methyl-3,6-dioxa-7-octene)sulfonyl fluoride, Ethanesulfonyl fluoride,2-(1-(difluoro((trifluoroethenyl)oxy)methyl)-1,2,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoro, 1,1,2,2-Tetrafluoro-2-(1,2,2-trifluoro-1-(trifluoromethyl)-2-((trifluorovinyl)oxy)ethoxy)ethanesulphonyl fluoride